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Old 09-23-2013, 02:43 PM   #61
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Originally Posted by thom4782 View Post
Oil starvation does not explain why the IMS failure rate of a sealed single row IMS bearing is 7 percentage points higher than its dual row counterpart rate of nearly 1%..
where are you getting this 1% and 7%?

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Old 09-23-2013, 03:14 PM   #62
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where are you getting this 1% and 7%?
Check this chart he posted here.

Autoweek Words on IMS
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Old 09-23-2013, 03:17 PM   #63
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Do you know why they change it to roller bearing? is it because of assembly issue?
The other side of the IMS shaft has the lapped bearing and the 8mm key that drives the oil pump, so there is plenty of lubrication on that side of the engine. It does cost money to cast into the block the oil passages. Plus it is easy to the drive cage bearing into the block on the flywheel side so you have speed of assembly. The original duel row bearing is only use by Porsche, to save more cost after they thought it was safe to build cars that way, they started to use an over the counter single row bearing that is also used in a GM alternator I believe and that is when things started to go "Tic Tic Boom!!''
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Old 09-23-2013, 03:45 PM   #64
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The total failure rates - dual 1% and single 8% - were provided during the discovery process of the IMS class action lawsuit. The 7% is the incremental difference between to two.
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Old 09-23-2013, 05:22 PM   #65
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Check this chart he posted here.

Autoweek Words on IMS
Those stats are for failures tracked by Porsche through their engine replacement program.
They leave out the mountain of cars Porsche had no dealing with with post warranty where owners were entirely on their own. There are far too many variables left out to put any weight behind the percentages in the Porsche numbers beyond that single bearing cars fail far more often than dual row. Its pure guessing to attempt to decipher the technical cause based on the imprecise degree of separation. For instance a dual row bearing car may catch up to a single row bearing car in terms of probability of failure if given enough time or mileage without addressing the bearing. I can not think of a more difficult statistical probability to pin down due to the infinite number of underlying variables. Its like parachute jumping over Normandy in WWII.
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Old 09-23-2013, 06:15 PM   #66
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OK, think of the 1% and 8% as lower bounds on actual rates across all cars.

It doesn't change my points. They address the situation where the IMS bearing fails first, which leads to subsequent damage of other engine parts.

I do recognize, however, there are a number of failure modes where another part fails first, such as a chain rail breaking, that subsequently leads to the IMS bearing destroying itself as a consequence.
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Old 09-23-2013, 06:27 PM   #67
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How is the bearing-free IMS Solution different from the bearing-free redesign in the 9A1 "solution"?
The 9a1 engine drives the cams directly from the crankshaft. Pictures of the internals can be found on our facebook page under the album "4.2 DFI Beast". I am putting together a WTI Engine Mechanical Class for the 9a1 and that will be available in May of 2014. Along with it will come some better illustrations.
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Old 09-24-2013, 06:50 AM   #68
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Those stats are for failures tracked by Porsche through their engine replacement program.
There are far too many variables left out to put an For instance a dual row bearing car may catch up to a single row bearing car in terms of probability of failure if given enough time or mileage without addressing the bearing.
This is true , the bigger duel row has more bearing to wear away before failure, it takes longer and with more bearing material being circulated throughout the entire engine there is more secondary engine damage.

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Old 09-24-2013, 08:28 AM   #69
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I see. Thanks.
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Originally Posted by kashmir View Post
The other side of the IMS shaft has the lapped bearing and the 8mm key that drives the oil pump, so there is plenty of lubrication on that side of the engine. It does cost money to cast into the block the oil passages. Plus it is easy to the drive cage bearing into the block on the flywheel side so you have speed of assembly. The original duel row bearing is only use by Porsche, to save more cost after they thought it was safe to build cars that way, they started to use an over the counter single row bearing that is also used in a GM alternator I believe and that is when things started to go "Tic Tic Boom!!''
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Old 09-24-2013, 09:06 AM   #70
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Would it be my best interest to "Exclude Myself" instead of "Object" to the Class Action Settlement when my 2003 with 80k miles has been "placed in service" (registered) for more than 10 years?
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Old 09-24-2013, 09:55 AM   #71
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Those stats are for failures tracked by Porsche through their engine replacement program. They leave out the mountain of cars Porsche had no dealing with with post warranty where owners were entirely on their own. There are far too many variables left out to put any weight behind the percentages in the Porsche numbers beyond that single bearing cars fail far more often than dual row. Its pure guessing to attempt to decipher the technical cause based on the imprecise degree of separation. WWII.
I disagree with your comments that one can't "put any weight behind the percentages" and "it's pure guessing" tu use the Porsche numbers because statistics show that the uncertainties between Porsche reported failure rates and actual ones are likely very small to make meaningful differences.

For example, if Porsche used just one-fourth of all actual dual row failures when calculating its reported rate, which is very likely the case, then one can say with 95% certainty that the actual failure rate for all dual row cars lies somewhere between 0.9% and 1.1%.

Moreover, if Porsche used just one-sixth of all actual single row failures when calculating its rate, which is even more likely the case, one can say with 95% confidence that the actual rate of single row failures lies somewhere between 7.6% and 8.4%.

These differences - 1% versus 0.9% to 1.1% and 8% versus 7.6% to 8.4% - are just too small to disregard the reported Porsche numbers.
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Old 09-24-2013, 10:01 AM   #72
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Would it be my best interest to "Exclude Myself" instead of "Object" to the Class Action Settlement when my 2003 with 80k miles has been "placed in service" (registered) for more than 10 years?
If enough people object, the terms of the settlement may get changed for the better for people like yourself. If you exclude yourself, you'd have to sue Porsche on your own to get any benefit and the cost of doing that will be greater than buying a new motor. Personally, I objected because my car like yours is outside the 10 year window.
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Old 09-24-2013, 08:11 PM   #73
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If enough people object, the terms of the settlement may get changed for the better for people like yourself. If you exclude yourself, you'd have to sue Porsche on your own to get any benefit and the cost of doing that will be greater than buying a new motor. Personally, I objected because my car like yours is outside the 10 year window.
To object is a gamble too as there is no way of knowing the outcome and it may end up that you lose your right to sue Porsche later on. I still need to think it through as to what I'm gonna do but do you mind sharing what did you state in your objection letter? Thanks!
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Old 09-24-2013, 08:20 PM   #74
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Old 09-25-2013, 07:18 AM   #75
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because statistics show that the uncertainties between Porsche reported failure rates and actual ones are likely very small to make meaningful differences.
This would be true if the cars lived in a vacuum post-warranty. But they are all subjected to very different types of driving and engine care which can drastically affect the number of failures. The more mileage goes on the engine, the more those variables can sway the numbers. Hence, within the specific set of numbers you are using, (and I'm not sure which statistics you are comparing those to) you could be correct but the problem is that you are using Porsche's numbers which were not vetted or subject to review by an independent third party and certainly not held to a standard that could pass any sort of regulatory muster. The fact that Porsche can't even tell you which cars had dual row bearings leaves me with serious doubts about the accurracy and thoroughness of their reporting as a base line.

To me the main proble with analyzing these stats for 'beyond general' analysis is that this is a dynamic failure, it's not like a product testing for light bulb where an item is subjected to the exact same rigors accross each test sample. Every test of the IMS bearing (driver habits) is different to the next test with no way of measuring that variance.
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Old 09-25-2013, 07:29 AM   #76
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The Porsche reported numbers are based on a sample of all IMS failures occurring in all 986s up through the 2005 model year. A statistical analysis of that information can reveal the range of possible failure rates for all Boxsters regardless of whether they were reported to Porsche on not. The ranges in my earlier note reflect the results of that statistical analysis.

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Old 09-25-2013, 09:03 PM   #77
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To object is a gamble too as there is no way of knowing the outcome and it may end up that you lose your right to sue Porsche later on. I still need to think it through as to what I'm gonna do but do you mind sharing what did you state in your objection letter? Thanks!
No, not true. If you object you will still stay in the Class. Actually you can only object if you stay in the Class, if you exclude yourself you cannot object anymore. Read the notice carefully.
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Old 09-25-2013, 09:14 PM   #78
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I think someone mentioned objecting through Email instead of writing and posting a letter. Since I'm a lazy bum I'd like to know how I'm supposed to do that.

My objection is against the 10 years max age of the car and against the pathetic 25% reimbursement when the car is bought used.

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